Solutions for 2022, as well as 2015-2018 and 2019 up to day 11

2015/day01-not_quite_lisp/Cargo.toml

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+[package]
+name = "day01-not_quite_lisp"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2015/day01-not_quite_lisp/challenge.txt

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+\--- Day 1: Not Quite Lisp ---
+----------
+
+Santa was hoping for a white Christmas, but his weather machine's "snow" function is powered by stars, and he's fresh out! To save Christmas, he needs you to collect *fifty stars* by December 25th.
+
+Collect stars by helping Santa solve puzzles. Two puzzles will be made available on each day in the Advent calendar; the second puzzle is unlocked when you complete the first. Each puzzle grants *one star*. Good luck!
+
+Here's an easy puzzle to warm you up.
+
+Santa is trying to deliver presents in a large apartment building, but he can't find the right floor - the directions he got are a little confusing. He starts on the ground floor (floor `0`) and then follows the instructions one character at a time.
+
+An opening parenthesis, `(`, means he should go up one floor, and a closing parenthesis, `)`, means he should go down one floor.
+
+The apartment building is very tall, and the basement is very deep; he will never find the top or bottom floors.
+
+For example:
+
+* `(())` and `()()` both result in floor `0`.
+* `(((` and `(()(()(` both result in floor `3`.
+* `))(((((` also results in floor `3`.
+* `())` and `))(` both result in floor `-1` (the first basement level).
+* `)))` and `)())())` both result in floor `-3`.
+
+To *what floor* do the instructions take Santa?
+
+Your puzzle answer was `232`.
+
+\--- Part Two ---
+----------
+
+Now, given the same instructions, find the *position* of the first character that causes him to enter the basement (floor `-1`). The first character in the instructions has position `1`, the second character has position `2`, and so on.
+
+For example:
+
+* `)` causes him to enter the basement at character position `1`.
+* `()())` causes him to enter the basement at character position `5`.
+
+What is the *position* of the character that causes Santa to first enter the basement?
+
+Your puzzle answer was `1783`.
+
+Both parts of this puzzle are complete! They provide two gold stars: \*\*
+
+At this point, all that is left is for you to [admire your Advent calendar](/2015).
+
+If you still want to see it, you can [get your puzzle input](1/input).

2015/day01-not_quite_lisp/src/lib.rs

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+use std::fs::read_to_string;
+
+fn read_file(name: &str) -> String {
+    read_to_string(name).expect(&format!("Unable to read file: {}", name)[..])
+}
+
+fn char_to_floor(c: char) -> isize {
+    match c { 
+        '(' => 1, 
+        ')' => -1, 
+        _ => 0,
+    }
+}
+
+pub fn final_floor(input: &str) -> isize {
+    input.chars().map(char_to_floor).sum()
+}
+
+pub fn first_basement_pos(input: &str) -> usize {
+    let mut floors = input.chars().scan(0, |curr_floor, c| { *curr_floor += char_to_floor(c);Some(*curr_floor) } );
+    floors.position(|i| i==-1).expect("Never reached Floor -1") + 1
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_sample() {
+        let sample_input = read_file("tests/sample_input");
+        let expected = [0, 0, 3, 3, 3, -1, -1, -3, -3];
+        for (line_number, line) in sample_input.lines().enumerate() {
+            assert_eq!(final_floor(line), expected[line_number]);
+        }
+        let samples_2 = [")", "()())"];
+        let expected_2 = [1, 5];
+        for (sample_number, sample) in samples_2.iter().enumerate() {
+            assert_eq!(first_basement_pos(sample), expected_2[sample_number]);
+        }
+    }
+
+    #[test]
+    fn test_challenge() {
+        let challenge_input = read_file("tests/challenge_input");
+        assert_eq!(final_floor(&challenge_input), 232);
+        assert_eq!(first_basement_pos(&challenge_input), 1783);
+    }
+}

2015/day01-not_quite_lisp/tests/sample_input

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+(())
+()()
+(((
+(()(()(
+))(((((
+())
+))(
+)))
+)())())